Endoscopic infusion needle having dual distal stops

ABSTRACT

An endoscopic infusion needle device includes a catheter within which an injection tube having a distal injection needle is slideably disposed. A proximal actuating handle is coupled to the proximal ends of the catheter and the injection tube, and a distal stopping structure is provided on distal portions of the catheter and the injection tube. In one embodiment, the stopping structures include a rigid elongate skeletal structure occupying a portion of the annular space between the tube and the catheter, and an annular band on the tube which resides within the skeletal structure. The skeletal structure fits tightly within the cannula, allows irrigation fluid to pass through the annular space between the tube and the catheter to exit the distal end of the catheter, prevents the annular band from escaping through the proximal end or the distal end of the skeletal structure, and maintains the tube in substantial axial alignment with the catheter. The annular band is located such that when the tube is moved proximally, the distal end of the injection needle is safely housed within the skeletal structure when the annular band is stopped by the skeletal structure; and, when the tube is moved distally, the distal end of the needle extends approximately 4-6 mm beyond the distal end of the skeletal structure when the annular band is stopped by the skeletal structure.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to endoscopic medical devices. More particularly,the invention relates to an endoscopic infusion device having a needlewhich is movable within an outer tube from a first position to a secondposition.

2. State of the Art

Endoscopic infusion needle devices are used in the treatment of variousdigestive disorders to control bleeding or potential bleeding lesions inthe esophagus, stomach, duodenum, and colon. The state of the artdevices include a relatively long catheter, typically having an overalllength of about 200 cm, within which an inner injection tube having adistal injection needle is slideably disposed. A proximal actuatinghandle is coupled to the catheter and the injection tube for moving onerelative to the other. Fluid access to the injection tube is typicallyprovided via a luer connector on the handle. In addition, a second luerconnector is usually provided on the handle for introducing a salineirrigant into the annular space between the catheter and the injectiontube.

Endoscopic infusion needle devices are typically delivered to aninjection site through the lumen of an endoscope. In order to protectthe lumen of the endoscope from damage, the handle of the infusionneedle device is manipulated to withdraw the distal injection needleinto the lumen of the catheter before inserting the device into theendoscope. This is important to prevent exposure of the sharp point ofthe injection needle as the device is moved through the lumen of theendoscope. When the distal end of the infusion needle device is locatedat the injection site, its handle is again manipulated to move theinjection needle distally out of the lumen of the catheter. Whenadvanced to the most distal position, the exposed portion of theinjection needle should be approximately 4-6 mm in length. The injectionprocedure is often preceded by washing the site with saline in order toclear the field of view before piercing the injection site with theneedle. The saline wash is delivered via the annular space between thecatheter and the injection tube. After the injection site has beenpierced, a sclerosing agent or vasoconstrictor composition is deliveredthrough the injection tube and the needle into the injection site. Theprocedure may be performed at several injection sites before theinjection needle device is removed from the endoscope. Betweeninjections, however, the needle is withdrawn into the catheter toprevent inadvertent punctures or needle pricks.

The state of the art endoscopic infusion needle devices all suffer fromsimilar design problems which are related to the movement of the needleinto and out of the catheter. For example, it is difficult to assurethat the injection needle will remain within the catheter when it iswithdrawn, or to assure that the injection needle will not puncture thewall of the catheter during movement of the device through theendoscope. The reason for these problems is related to the dimensions ofthe device and the often tortuous path provided by the lumen of theendoscope. As mentioned above, the desired relative movement of theneedle and the catheter is only on the order of 10 mm, whereas theoverall length of the device is on the order of two hundred times thatamount. Thus, the movement of the proximal ends of the catheter and theinjection tube by an amount on the order of 10 mm cannot assure that thedistal ends of the catheter and the injection tube will move exactly thesame amount without requiring exacting tolerances. This issue isexacerbated by the tortuous path taken through the endoscope by thedevice. This tortuous path also causes the injection needle to bedeflected relative to the axis of the catheter such that the sharp pointof the needle touches the inner wall of the catheter. As the device ismoved through the endoscope, it is thereby possible for the injectionneedle to puncture the catheter wall, rendering the device inoperative,and possibly damaging the lumen of the endoscope.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide an endoscopicinfusion needle device which assures that the distal ends of thecatheter and the injection tube can be moved relative to each otherbetween two well-defined positions.

It is also an object of the invention to provide an endoscopic infusionneedle device which assures that the sharp end of the injection needlewill not contact the inner wall of the catheter.

It is another object of the invention to provide an endoscopic infusionneedle device which is inexpensive to manufacture.

It is still another object of the invention to provide an endoscopicinfusion needle device which does not require exacting tolerances toassure the well-defined positions of the catheter and the injectiontube.

In accord with these objects which will be discussed in detail below,the endoscopic infusion needle device of the present invention includesa relatively long catheter within which an inner injection tube having adistal injection needle is slideably disposed. A proximal actuatinghandle is coupled to the proximal ends of the catheter and the injectiontube for moving one relative to the other, and distal stoppingstructures are provided on distal portions of the catheter and theinjection tube. Fluid access to the injection tube is provided via aluer connector on the handle, and a second luer connector is provided onthe handle for introducing a saline irrigant into the annular spacebetween the catheter and the injection tube. According to one embodimentof the invention, the distal stopping structures include a rigidelongate skeletal structure which is inserted into the distal end of thecatheter and which occupies a portion of the annular space between theinjection tube and the catheter wall, and an annular band on a portionof the injection tube which resides within the skeletal structure. Theskeletal structure is dimensioned such that it fits tightly within thecannula, allows irrigation fluid to pass through the annular spacebetween the injection tube and the catheter and to exit the distal endof the catheter, and prevents the annular band from escaping through theproximal end or the distal end of the skeletal structure. In addition,the skeletal structure is dimensioned to maintain the injection needlein substantial axial alignment with the catheter. The annular band islocated on the injection tube such that when the injection tube is movedproximally relative to the catheter, the distal end of the injectionneedle is safely housed within the skeletal structure when the annularband is stopped by the skeletal structure; and, when the injection tubeis moved distally relative to the catheter, the distal end of theinjection needle extends approximately 4-6 mm beyond the distal end ofthe skeletal structure when the annular band is stopped by the skeletalstructure. According to other embodiments of the invention, two annularbands are provided on the injection tube and one or more stoppingstructures are provided within the cannula.

The distal stopping structure according to the invention provides apositive well-defined proximal stopping location and a positivewell-defined distal stopping location for the injection needle. Inaddition, several embodiments of the stopping structure provide an axialalignment for the injection needle which prevents the needle frompuncturing the catheter.

Additional objects and advantages of the invention will become apparentto those skilled in the art upon reference to the detailed descriptiontaken in conjunction with the provided figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a broken side elevation view in partial section of a firstembodiment of an endoscopic infusion needle device according to theinvention;

FIG. 2 is an enlarged broken side elevation view in partial section ofthe distal end of the infusion needle device of FIG. 1 in a retractedposition;

FIG. 3 is an enlarged broken side elevation view in partial section ofthe distal end of the infusion needle device of FIG. 1 in an extendedposition;

FIG. 4 is a perspective view of the coil stiffening and needle stoppingstructure of the infusion needle device of FIGS. 1-3;

FIG. 5 is an exploded perspective view of the coil stiffening and needlestopping structure of the infusion needle device of FIGS. 1-3;

FIG. 6 is an enlarged broken side elevation view in partial section ofthe distal end of a second embodiment of an infusion needle deviceaccording to the invention;

FIG. 6a is a cross sectional view taken along line 6A--6A in FIG. 6;

FIG. 7 is an enlarged broken side elevation view in partial section ofthe distal end of a third embodiment of an infusion needle deviceaccording to the invention;

FIG. 7a is a cross sectional view taken along line 7A--7A in FIG. 7;

FIG. 8 is an enlarged broken side elevation view in partial section ofthe distal end of a fourth embodiment of an infusion needle deviceaccording to the invention; and

FIG. 8a is a cross sectional view taken along line 8A--8A in FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIGS. 1 through 3, an endoscopic infusion needle device10 according to the invention includes a relatively long flexiblecatheter 12 having a proximal end 14, a distal end 16, and defining alumen 18. As shown, the catheter 12 is a steel coil covered with a PTFE,FEP or polyolefin sheath 20 along substantially its entire length. Aflexible, preferably metallic injection tube 22 having a proximal end24, a distal end 26, and defining an injection lumen 28 is slideablydisposed within the lumen 18 of the catheter 12 and defines an annularspace 19 between the tube 22 and the catheter 12. The distal end 26 ofthe injection tube 22 is provided with an injection needle 30 which isin fluid communication with the injection lumen 28 of the injection tube22.

The proximal ends 14, 24 of the catheter and the injection tube arecoupled to an actuation handle 32 which includes a central shaft 34 anda displaceable spool 36. The proximal end of the shaft 34 is providedwith a thumb ring 38 and a longitudinal bore 40 is provided at thedistal end of the shaft 34. A longitudinal slot 42 extends from theproximal end of bore 40 to a point distal of the thumb ring 38. Thedisplaceable spool 36 is provided with a cross member 44 which passesthrough the slot 42 in the central shaft 34. The proximal end 14 of thecatheter 12 is coupled to the cross member 44 which is provided with afluid conduit 46 terminating in a luer connector 48. The fluid conduit46 provides a fluid path from the luer 48 to the lumen 18 of thecatheter 12. An O-ring 49 in the cross member 44, proximal of the fluidconduit 46, seals the annulus between the catheter 12 and the injectiontube 22. The proximal end 24 of the injection tube 22 is coupled to aproximal portion 50 of the shaft 34 which is intermediate of the thumbring 38 and the slot 42. The portion 50 is provided with a fluid conduit52 terminating in a luer connector 54 which provides a fluid path fromthe luer to the injection lumen 28 of the injection tube 22.

From the foregoing, those skilled in the art will appreciate that whenthe thumb ring 38 and the spool 36 are moved toward each other, theinjection tube 22 will be axially displaced relative to the catheter 12such that the needle 30 extends out of the distal end of the catheter 12as shown in FIG. 3. When the thumb ring 38 and the spool 36 are movedaway from each other, the injection tube 22 will be axially displacedrelative to the catheter 12 such that the needle 30 is drawn into thedistal end of the catheter 12 as shown in FIGS. 1 and 2. Furthermore, itwill be appreciated that a source of irrigating fluid (not shown) may becoupled to the luer 48 and the irrigating fluid will be directed throughthe lumen 18 of the catheter in the annular space defined by theinjection tube 22 and the catheter 12 and will exit from the distal endof the catheter. In addition, it will be appreciated that a source ofinjection fluid (not shown) may be coupled to the luer 54 and theinjection fluid will be directed through the lumen 28 of the injectiontube and will exit from the distal end of the injection needle 30.

According to a first embodiment of the invention, a distal portion ofthe catheter 12 is provided with a rigid elongate skeletal structure 60which is inserted in the distal end of the catheter 12 and whichoccupies a portion of the annular space between the injection tube 22and the catheter 12. A distal portion of the injection tube 22 or aproximal portion of the injection needle 30 is provided with an annularband 62 which resides within the skeletal structure 60. As described inmore detail below with reference to FIGS. 4 and 5, the skeletalstructure 60 is dimensioned such that it fits tightly within thecatheter 12, allows irrigation fluid to pass through the annular spacebetween the injection tube 22 and the catheter 12 and to exit the distalend of the catheter, and prevents the annular band 62 from escapingthrough the proximal end or the distal end of the skeletal structure 60.In addition, the skeletal structure is dimensioned to maintain theinjection tube 22 and the needle 30 in substantial axial alignment withthe catheter 12. The annular band 62 is located such that when theinjection tube is moved proximally relative to the catheter, as shown inFIG. 2, the distal end of the injection needle 30 is safely housedwithin the skeletal structure when the annular band 62 is stopped by theskeletal structure. When the injection tube 22 is moved distallyrelative to the catheter 12, as shown in FIG. 3, the distal end of theinjection needle extends approximately 4-6 mm beyond the distal end ofthe skeletal structure 60 when the annular band 62 is stopped by theskeletal structure.

Turning now to FIGS. 4 and 5, according to a presently preferredembodiment, the skeletal structure 60 includes a proximal cylindricalmember 64, a distal cylindrical member 66, and four longitudinal outerstruts or splines 68, 70, 72, 74 which connect the cylindrical members64, 66. The struts are arranged at regular intervals around the outersurfaces of the cylindrical members and are intended to center thecylindrical members 64, 66 while providing a fluid flow path. The struts68, 70, 72, 74 are preferably provided with stepped distal portions 68a,70a, 72a, 74a which rise abruptly and form a seat for receiving thedistal end of the catheter 12 and then curve inward to form a smoothdistal end. According to the presently preferred embodiment, theskeletal structure 60 is formed from two identical members 60a, 60b withmating pegs 61a, 61b, 67a, 67b and holes 65a, 65b, 69a, 69b, and whichare bonded together.

Referring once again to FIGS. 2 and 3, and in view of the foregoing, itwill be appreciated that the diameter of the proximal cylindrical member64 of the skeletal structure 60 is large enough to allow free passage ofthe injection tube 22, but too small to allow the passage of the annularband 62. Similarly, the diameter of the distal cylindrical member 66 islarge enough to allow free passage of the injection needle 30, but toosmall to allow the passage of the annular band 62. According to apresently preferred embodiment, the diameter of the injection tube 22 isapproximately 0.028 inches; the diameter of the injection needle isapproximately 0.020 inches (25G); and the diameter of the annular bandis approximately 0.035 inches. The space between the struts issufficient to allow passage of irrigant through the distal end of thecatheter.

From the foregoing and with reference to FIGS. 1-5, generally, it willbe appreciated that the skeletal structure 60 and the annular band 62provide a positive well-defined proximal stopping location (FIG. 2) anda positive well-defined distal stopping location (FIG. 3) for theinjection needle 30. In addition, the skeletal structure provides anaxial alignment for the injection needle 30 which prevents the needlefrom puncturing the catheter 12. While the first embodiment of theinvention has been shown in conjunction with a coated steel coilcatheter, it will be appreciated that other types of catheters could beused, such as flexible plastic catheters.

FIGS. 6 and 6a show a second embodiment 110 of the invention where partssimilar to the first embodiment are indicated by similar referencenumerals increased by 100. According to the second embodiment, thedistal end of the injection tube 122 is provided with two spaced apartannular bands 162, 163. At least one stopping washer 160 is placedbetween adjacent coils of the catheter 112 such that the washer(s)reside between the annular bands 162, 163. As seen best in FIG. 6a, thestopping washer 160 is substantially disk shaped with a radial cutout160a and two side cutouts 160b, 160c. When the washer 160 is insertedradially in between adjacent coils of the catheter 112, the radialcutout 160a receives the injection tube 122 and the side cutouts 160b,160c allow the passage of irrigant through the distal end of thecatheter 112. It will be appreciated that the dimensions of the radialcutout 160a are such that the washer prevents distal passage of theproximal annular band 162 and prevents proximal passage of the distalannular band 163. Preferably two washers are used with their radialcutouts oriented in opposite directions to provide an axial alignment ofthe injection tube 122 with the catheter 112. From the foregoing, thoseskilled in the art will appreciate that the washer(s) 160 and the bands162, 163 cooperate to provide a positive well-defined proximal stoppinglocation for the needle 130 wherein the needle is shrouded by thecatheter 112 and a positive well-defined distal stopping location wherethe injection needle 130 extends approximately 4-6 mm out of thecatheter 112.

FIGS. 7 and 7a show a third embodiment 210 of the invention where partssimilar to the first embodiment are indicated by similar referencenumerals increased by 200. The third embodiment of the invention ispreferably used with a plastic catheter. According to the thirdembodiment, the distal end of the injection tube 222 is provided withtwo spaced apart annular bands 262, 263. A strutted barbed cylindricalstop 260 is pressed into the distal end of the catheter 212 such thatthe stop resides between the annular bands 262, 263. As seen best inFIG. 7a, the stop 260 has a central cylinder 264 with four outer struts268, 270, 272, 274. Preferably, each strut is provided with barbs 268a,270a, 272a, 274a. When the stop 260 is inserted axially into the distalend of the catheter 212, the barbed struts engage the interior of thecatheter after several hours of cold setting. Alternatively, thecatheter may be dilated with heat before inserting the stop. It will beappreciated that the dimensions of the cylinder 264 are such that itprevents distal passage of the proximal annular band 262 and preventsproximal passage of the distal annular band 263. The struts 268, 270,272, 274 are dimensioned and arranged to allow free passage of irrigantthrough the distal end of the catheter. From the foregoing, thoseskilled in the art will appreciate that the stop 260 and the bands 262,263 cooperate to provide a positive well-defined proximal stoppinglocation for the needle 230 wherein the needle is shrouded by thecatheter 212 and a positive well-defined distal stopping location wherethe injection needle 230 extends approximately 4-6 mm out of thecatheter 212.

FIGS. 8 and 8a show a fourth embodiment 310 of the invention where partssimilar to the first embodiment are indicated by similar referencenumerals increased by 300. The fourth embodiment of the invention isshown with a plastic catheter 312, but may be used with any type ofcatheter. According to the fourth embodiment, the distal end of theinjection tube 322 is provided with two spaced apart annular bands 362,363 and a distal stopping structure 360 is inserted into the distal endof the catheter 312. The stopping structure has a proximal innercylinder 364 and an outer cylinder 366 having a reduced diameterproximal portion 366a which fits into the distal end of the catheter312. The proximal inner cylinder 364 is coupled to the outer cylinder byfour radial struts 368, 370, 372, 374 which define four longitudinalfluid paths 368a, 370a, 372a, 374a between the inner cylinder 364 andthe outer cylinder 366. The diameter of the inner cylinder 364 is suchthat it prevents distal passage of the proximal annular band 362 andprevents proximal passage of the distal annular band 363. When used witha plastic catheter, the reduced diameter portion 366a of the outercylinder is solvent bonded to the catheter. When used with a steel coilcatheter, the reduced diameter portion 366a may be provided with outerthreads (not shown) to engage the coils of the catheter. The length ofthe outer cylinder 366 and the location of the bands 362, 364 are chosenso that the inner cylinder and the bands cooperate to provide a positivewell-defined proximal stopping location for the needle 330 wherein theneedle is shrouded by the outer cylinder 360 and a positive well-defineddistal stopping location where the injection needle 330 extendsapproximately 4-6 mm out of the outer cylinder 360.

There have been described and illustrated herein several embodiments ofan endoscopic infusion needle device. While particular embodiments ofthe invention have been described, it is not intended that the inventionbe limited thereto, as it is intended that the invention be as broad inscope as the art will allow and that the specification be read likewise.Thus, while particular types of catheters have been disclosed, it willbe appreciated that other catheters could be utilized. Also, whileseveral specific distal stopping structures have been shown, it will berecognized that other types of distal stopping structures could be usedwith similar results obtained. Moreover, while particular configurationshave been disclosed in reference to the proximal handle, it will beappreciated that other configurations could be used as well. Inaddition, while certain structures have been identified as beingcylindrical, it will be understood than a substantially cylindricalstructure can achieve the same results. Similarly, while one of thestopping structures has been described as an annular band, it will beappreciated that other types of surface structures such as bumps orstruts could be used. Furthermore, while the device has been disclosedas having specific dimensions, it will be understood that otherdimensions can achieve the same or similar function as disclosed herein.

It will therefore be appreciated by those skilled in the art that yetother modifications could be made to the provided invention withoutdeviating from its spirit and scope as so claimed.

We claim:
 1. An endoscopic infusion needle device, comprising:a) acatheter having a proximal end, a distal end, and defining a firstlumen; b) an injection tube having a proximal end, a distal end, anddefining a second lumen, said injection tube extending at leastpartially through said first lumen and defining an annular space betweensaid injection tube and said catheter; c) an injection needle coupled tosaid distal end of said injection tube, said injection needle having aninjection lumen in fluid communication with said second lumen; d) aproximal actuating means coupled to said proximal end of said catheterand to said proximal end of said injection tube for axially displacingsaid catheter and said injection tube relative to one another; e)injection fluid port means coupled to said second lumen for introducingan injection fluid into said injection lumen; f) a first distal stoppingstructure coupled to a distal portion of said catheter, wherein at leasta portion of the first distal stopping structure extends within thecatheter lumen; and g) a second distal stopping structure coupled to atleast one of said injection tube and said injection needle, wherein atleast a portion of said second distal stopping structure is moveablewith the injection tube and needle within the catheter lumen, andwherein said first and second distal stopping structures cooperate withone another to provide a positive well-defined proximal stoppinglocation wherein said injection needle is shrouded by said catheter, andto provide a positive well-defined distal stopping location wherein saidinjection needle extends out of said catheter.
 2. An endoscopic infusionneedle device according to claim 1, wherein:said first distal stoppingstructure includes at least one substantially cylindrical member havinga plurality of substantially radial exterior struts, said at least onesubstantially cylindrical member being arranged inside said first lumensuch that said struts engage said catheter and at least one of saidinjection tube and said injection needle passes through said at leastone substantially cylindrical member, and said second distal stoppingstructure includes at least one annular structure coupled to one of saidinjection tube and said injection needle.
 3. An endoscopic infusionneedle device according to claim 2, wherein:said first distal stoppingstructure includes two substantially cylindrical members having aplurality of substantially radial exterior struts, said twosubstantially cylindrical members being arranged inside said first lumensuch that one of said injection tube and said injection needle passesthrough said two substantially cylindrical member and said struts engagesaid catheter, and said at least one annular structure resides inbetween said two substantially cylindrical members.
 4. An endoscopicinfusion needle device according to claim 3, wherein:said twosubstantially cylindrical members are coupled to each other by aplurality of splines.
 5. An endoscopic infusion needle device accordingto claim 4, wherein:said first distal stopping structure extendspartially out of said distal end of said catheter.
 6. An endoscopicinfusion needle device according to claim 5, wherein:said first distalstopping structure has a smooth distal end.
 7. An endoscopic infusionneedle device according to claim 4, wherein:said first distal stoppingstructure is made of two identical pieces.
 8. An endoscopic infusionneedle device according to claim 1, wherein:said second distal stoppingstructure includes two annular structures, each coupled to one of saidinjection tube and said injection needle, and said first distal stoppingstructure resides in between said two annular structures.
 9. Anendoscopic infusion needle device according to claim 8, wherein:saidfirst distal stopping structure includes a substantially cylindricalmember having a plurality of outer struts.
 10. An endoscopic infusionneedle device according to claim 9, wherein:said struts includeoutwardly extending barbs.
 11. An endoscopic infusion needle deviceaccording to claim 9, wherein:said struts are arranged substantiallyradially relative to said substantially cylindrical member.
 12. Anendoscopic infusion needle device according to claim 8, wherein:saidfirst distal stopping structure includes a washer having a radialopening.
 13. An endoscopic infusion needle device according to claim 1,further comprising:h) irrigation fluid port means coupled to said firstlumen for introducing an irrigant into said annular space, wherein saidfirst and second distal stopping structures permit said irrigant to flowout of said distal end of said catheter.
 14. An endoscopic infusionneedle device, comprising:a) a catheter having a proximal end, a distalend, and defining a first lumen; b) an injection tube having a proximalend, a distal end, and defining a second lumen, said injection tubeextending at least partially through said first lumen and defining anannular space between said injection tube and said catheter; c) aninjection needle coupled to said distal end of said injection tube, saidinjection needle having an injection lumen in fluid communication withsaid second lumen; d) a proximal actuating means coupled to saidproximal end of said catheter and to said proximal end of said injectiontube for axially displacing said catheter and said injection tuberelative to one another; e) injection fluid port means coupled to saidsecond lumen for introducing an injection fluid into said injectionlumen; f) a first distal stopping structure coupled to a distal portionof said catheter, said first distal stopping structure having a firstsubstantially cylindrical portion extending beyond said distal end ofsaid catheter, wherein at least a portion of the first distal stoppingstructure extends within the catheter lumen; and g) a second distalstopping structure coupled to at least one of said injection tube andsaid injection needle, wherein at least a portion of said second distalstopping structure is moveable with the injection tube and needle withinthe catheter lumen, and whereinsaid first and second distal stoppingstructures cooperate with one another to provide a positive well-definedproximal stopping location wherein said injection needle is shrouded bysaid first substantially cylindrical portion, and to provide a positivewell-defined distal stopping location wherein said injection needleextends out of said first substantially cylindrical portion.
 15. Anendoscopic infusion needle device according to claim 14, wherein:saidfirst distal stopping structure includes a second substantiallycylindrical portion residing within said first substantially cylindricalportion and coupled to said first substantially cylindrical portion by aplurality of struts, one said injection tube and said injection needleextending through said second substantially cylindrical portion.
 16. Anendoscopic infusion needle device according to claim 15, wherein:saidsecond distal stopping structure includes at least one annular structurecoupled to one of said injection tube and said injection needle.
 17. Anendoscopic infusion needle device according to claim 15, wherein:saidsecond distal stopping structure includes two annular structures, eachcoupled to one of said injection tube and said injection needle, saidsecond substantially cylindrical portion residing in between said twoannular structures.
 18. An endoscopic infusion needle device,comprising:a) a catheter having a proximal end, a distal end, anddefining a first lumen; b) an injection tube having a proximal end, adistal end, and defining a second lumen, said injection tube extendingat least partially through said first lumen and defining an annularspace between said injection tube and said catheter; c) an injectionneedle coupled to said distal end of said injection tube, said injectionneedle having an injection lumen in fluid communication with said secondlumen; d) a proximal actuating means coupled to said proximal end ofsaid catheter and to said proximal end of said injection tube foraxially displacing said catheter and said injection tube relative to oneanother; e) injection fluid port means coupled to said second lumen forintroducing an injection fluid into said injection lumen; f) a centeringstructure coupled to a distal portion of said catheter, whereinsaidcentering structure maintains said injection needle in substantial axialalignment with said distal portion of said catheter during movement ofsaid injection needle within said first lumen, wherein said centeringstructure includes means for limiting a range of motion of saidinjection needle relative to said catheter between a first positionwherein said injection needle is shrouded by said centering structure toa second position wherein said injection needle extends distally beyondsaid centering structure, and wherein the means for limiting a range ofmotion includes a first stopping structure attached to a portion of theneedle and moveable with said needle within said first lumen of saidcatheter.
 19. An endoscopic needle device according to claim 18,wherein:said centering structure includes a substantially rigidstructure, and wherein said injection needle is shrouded by saidsubstantially rigid structure in said first position, and said injectionneedle extends distally beyond said substantially rigid structure insaid second position.
 20. An endoscopic needle device according to claim19, wherein:said centering structure further includes a second stoppingstructure for engaging the first stopping structure attached to theneedle in order to provide a positive stop at at least one of said firstand second positions.
 21. An endoscopic infusion needle device,comprising:a) a catheter having a proximal end, a distal end, anddefining a first lumen; b) an injection tube having a proximal end, adistal end, and defining a second lumen, said injection tube extendingat least partially through said first lumen and defining an annularspace between said injection tube and said catheter; c) an injectionneedle coupled to said distal end of said injection tube, said injectionneedle having an injection lumen in fluid communication with said secondlumen; d) a proximal actuating means coupled to said proximal end ofsaid catheter and to said proximal end of said injection tube foraxially displacing said catheter and said injection tube relative to oneanother; e) a first distal stopping structure including at least onesubstantially cylindrical member having a plurality of substantiallyradial exterior struts, wherein said first distal stopping structure iscoupled to a distal portion of said catheter and said at least onesubstantially cylindrical member extends within the first lumen suchthat said struts engage the catheter and at least one of said injectiontube and said injection needle passes through said at least onesubstantially cylindrical member; and f) a second distal stoppingstructure including at least one annular structure coupled to at leastone of said injection tube and said injection needle, whereinsaid firstand second distal stopping structures cooperate with one another toprovide a positive well-defined proximal stopping location wherein saidinjection needle is shrouded by said catheter, and to provide a positivewell-defined distal stopping location wherein said injection needleextends out of said catheter.